Hi...
not necessarily Going to form implies a plan... for example in It's going to rain or she's going to have a baby...
The topic is quite complex, but Going to is both an intentional future and a "unavoidable" future, something that will surely happen
Bye

going to is preferred in spoken english and will in formal written english.

going to is used when we predict that something will happen because we have some evidence; or to talk about intentions or decisions

Will is to make a prediction based on our opinion or our past experience;
or in a formal style to talk about futur events that have been previously arranged; or when we state a decision made at the moment of speaking; or again to describe a future event that follow another.

ex:

i'm not feeling well. I think I'm going to be sick.
john is going to visit Paris next month. He showed me his plane tickets.

I'm sure you will have a good time with Bob.
" the 5.30 to London will leave from platform 4" ( announcement at a railway station)
"I think I will walk home" " that's a good idea!"
If you're ready , I will explain how it works

thanks a lot
in fact I saw in a grammar book that you should use will when you want to speak about something that you didn't decide in advance and be going to when you decided in advance
Is that right in usual langage?

I've always been told (and that's also what we find in grammar books - such as SWAN, which is, I think reliable), that when we make a decision at the time of speaking we should use "will" and that when it's been decided before we should use "be going to". Now...is it the same in "real life"? I had a discussion with some teachers today and we didn't seem to agree. So here are two sentences. I would like to know whether in each case "will" would be possible instead of "be going to" and vice versa.

1.- Did you remember to post the letter?
(opening her bag) - Oh dear! I forgot! I'm very sorry. I'll post it in the afternoon.

1. Not really; the sentence is most natural as written.
2. Yes, it's possible to switch to "will," but if you do, you reduce the imminence of your prediction.

In fact usage patterns for "I will do it" vs. "I am going to do it" are very, very similar to those of je le ferai vs. je vais le faire. This topic has been discussed before, and so I've transferred your question into an existing thread on the topic. You may find it helpful to read back through the previous posts.

This is amazing. I've been speaking English for 60 years and French for 50 years and the question never crossed my mind because (whatever the rule is) it's identical in both languages. No translating problem therefore no problem. Go with the flow.

I don't agree with the fact that it's the same in both languages...If the doorbell rings, what would you naturally say? "I'll open the door", or am I wrong? Then if on your way to the door someone asks you where you are going you could answer: I'm going to open the door.

In French in both cases you would say: je vais ouvrir la porte.

I just want to say that it's not 100 percent identical...

Being a native English speaker, what would you "naturally" say regarding the two examples that I gave:

1. - Did you remember to post my letter
- (opening her bag) Oh no! I forgot! I'll do ii in the afternoon. (desicion made at the time of speaking)

2. Look! He's going to fall off his bag (prediction made on outside evidence)

Ok, I admit that there is some non-equivalence when the action of physically "going" (moving in space) comes into play. "I am going to open the door" is either a statement in the present perfect continuous that you can make as you physically "go" towards the door.... or it is a plan, such as when you are describing how you will welcome someone arriving for a surprise birthday party. "I will open the door" is either a statement of insistence (I -- not you -- will be the one to open the door) or the answer to an (implied) question about who will get the door... what the wife says when her husband has his hands full with the kids, for example. If the door bell rings and you need to excuse yourself from the guests who have already arrived so that you can go answer, I think you'd say instead "I'll (just) go answer the door." Again, this is because of the overlap between "am going" used to indicate physical motion vs. "am going" used as a near future auxiliary. But I really feel that the vast majority of the time, the futur/futur proche distinction is essentially the same in both languages.

As for questions about your two example sentences, I already gave you my answer in post #19 above. Neither of them involve possible confusion with physically going from point A to point B, and both are most natural in the form you have chosen. A switch to the simple future is possible in #2, but not in #1.

How about this situation: an elderly lady drops her purse and starts to bend down with difficulty. You offer to pick it up so she doesn't have to.

English: Don't bother, I'll do it!
French: Laissez, je vais le faire!

This is a situation that implies a spur-of-the-moment decision, and with no possible confusion between "aller" as a future "proche" and "aller" as a motion from A to B. Clearly, in this case, English and French usage seem to diverge. There's no way you would say "je le ferai" in the French example.

Before someone objects: I do realize that in the English example, the key word is I (as opposed to "you"), so it would seem that the rest of the sentence, including the tense of the verb, doesn't really matter. However, I notice that people invariably would say "I"ll do it" and not "I'm going to do it" in this kind of situation.

This is a situation that implies a spur-of-the-moment decision, and with no possible confusion between "aller" as a future "proche" and "aller" as a motion from A to B. Clearly, in this case, English and French usage seem to diverge. There's no way you would say "je le ferai" in the French example.

Click to expand...

As I mentioned in my post above, we tend to use the future in English when we wish to insist upon the subject... which is just what you're doing here when you tell the old lady that you -- not she -- will pick up her dropped purse. This usage for insistence may be related to the fact that our English future is formed with an auxiliary verb ("will") that is linked to expression of the speaker's own will (=volonté). And I agree that we don't use the futur for this sort of insistence in French. So perhaps we can say that usage of the futur vs. futur proche is parallel in French and English 98% of the time... the exceptions being that English switches to the simple future in a couple of situations (insistence, or possible confusion with motion from A to B) when French uses the futur proche.

Before someone objects: I do realize that in the English example, the key word is I (as opposed to "you"), so it would seem that the rest of the sentence, including the tense of the verb, doesn't really matter.

Click to expand...

I don't understand that last bit. Why would the fact that the subject happens to be "I" make any difference? If you were telling the old lady that your son would pick up her purse for her, you'd certainly say "He'll pick that up" instead of "He is going to pick it up."

(...)
I don't understand that last bit. Why would the fact that the subject happens to be "I" make any difference? If you were telling the old lady that your son would pick up her purse for her, you'd certainly say "He'll pick that up" instead of "He is going to pick it up."

Click to expand...

What I meant was that some people might accuse me of comparing apples with oranges: the English sentence "I'll do it" is one that may translate "c'est moi qui le ferai" as well as "c'est moi qui vais le faire" because it is one of those sentences where the stress or the intonation (when you speak) or the bold type (when you write) gives a special status to one specific word ("I"), making it, so to speak, the whole point of the sentence. You can't do that in French unless you use additional words to emphasize one in particular. I don't feel that the sentence "je vais le faire" puts any particular emphasis on the subject being the whole point of the sentence in the same way as the English sentence does. I'm sorry I wasn't clear enough (and to be honest I'm not sure I'm clearer this time!)

1.- Did you remember to post the letter?
(opening her bag) - Oh dear! I forgot! I'm very sorry. I'll post it in the afternoon.

2. Look! That kid is going to fall off his bike!

Click to expand...

I disagree very slightly with jann on #2 here. Technically, you can switch to will, but the result is a strange sentence with no context that I can't imagine anyone saying. It's the "Look!" that forces the going to here. "Look! That kid will fall off his bike" is strange to me, while "Look! That kid will fall off his bike one day" is fine. Using the simple future requires additional context in my opinion.

But is the flipside true? My impression is that in #1 the futur proche is at least possible. Am I wrong about that?

As they have told you , the reason is because in the first three sentences people have planned those activities .
When it concerns to the fourth one , it´s an immediate action , not planned previously .